I am just writing to mention that I am currently working on GAP programs
which are intended to become an IntegralMeatAxe package later on.

I have got the basic arithmetique such as finding bases of sublattices,
finding smallest pure overlattices, finding nullspaces, finding the action
on sublattices and quotient lattices, and finding submodules generated by
sets of vectors. They are based on the ideas described in R.Parker's paper
mentioned by Steve.

But a good irreducibility test, in particular for the cases where the
endomorphism ring of an irreducible module is a proper skew field, and
an automatic chop program, where in particular the question of
entry explosion has to be addressed, are still under construction.

Hence for the time being the programs are in a state which does not allow
to make them publicly available. But I am very interested in trying my luck
on test examples which differ from the ones I usually encounter. Would it
help you, Dima, if you sent me a few of the examples you are working on?